1. Field of the Invention
The invention relates to a technique for filling a tank with gas.
2. Description of Related Art
A technique for determining a flow rate for gas filling, based on the pressure and the temperature in a tank prior to filling initiation and the temperature of the gas with which the tank is filled and in accordance with a map, when the tank is filled with the gas is available (Japanese Patent Application Publication No. 2011-406583). In addition, gas filling over a short period of time (hereinafter, referred to as “preliminary filling”) is performed prior to the gas filling for the tank (hereinafter, referred to as “main filling”) in this technique. A map to be used in the flow rate determination is selected from a plurality of maps based on an increment in the temperature and an increment in the pressure of the tank during the preliminary filling.
In the technique described above, the increment in the pressure that is measured during the preliminary filling is not sufficiently large with respect to the noise during the measurement in a case where the amount of the gas remaining in the tank is equal to or greater than a predetermined amount. Accordingly, the increment in the pressure of the tank during the preliminary filling may not be measured with accuracy. Additionally, it may be impossible to select an appropriate map and appropriately determine a flow rate for the main filling. In addition, reduction in apparatus size, cost reduction, resource conservation, facilitated filling, improvement in apparatus usability, and the like have been desired regarding gas filling techniques.